The state of the art for liquid extinguishing agents such as water and aqueous solutions is represented by fire-extinguishing systems where this extinguishing liquid is stored in extinguishing-agent tanks and is conveyed, using a suitable conveyor device such as a pump, through pipes to the extinguishing nozzles and is discharged by means of these onto the source of the fire or a space to be inerted.
Synthetic extinguishing agents are stored in a liquid state in pressure vessels. Since in most cases the intrinsic vapor pressure of the extinguishing agent is not sufficient to convey the extinguishing agents in the prescribed time through a pipeline and to ensure the requisite minimum nozzle pressure, in most cases pressure is applied using a gas, for example nitrogen. At the nozzles, the extinguishing agent evaporates, creating a gaseous extinguishing-agent/air mixture that extinguishes efficiently. Synthetic liquid extinguishing or inerting agents are extinguishing agents such as halogenated carbohydrates, fluorocarbons, fluoro ketones or synthetic liquids having comparable properties. All components of the extinguishing system (pipes, valves, tanks, nozzles) must be designed for the appropriate pressure of at least 25 bar. This requires a corresponding technical and financial effort. Also the pressurization used requires additional storage volume in the pressure vessel or additional pressure vessels having the gas for pressurization.
The document US 2002/027143 A1 reveals an extinguishing system with liquefied gas in an extinguishing tank and special spray nozzles. Here, the extinguishing agent is stored in the extinguishing tank at a pressure of up to 100 psig, relative to a room temperature of 25° C. The extinguishing agent is forced under high pressure through the pipeline network, by a propellant under high pressure that is stored in a separate tank and is introduced into the extinguishing-agent tank. The discharge of the extinguishing-agent amount is not controlled by a fire detection panel and/or control panel or by concentration sensors.
EP 0557275 B1 describes a fire-extinguishing method where various synthetic extinguishing agents are used to prevent a fire from starting in a closed space.
Use of N2 and CO2 for inerting is described in DE 44 32 346 C1.
DE 100 51 662 A1 describes a method for extinguishing a fire that has started inside a closed space, using nitrogen, pressure cylinders serving to keep and store this gas.
DE 10 2006 048 015 A1 describes a fire-extinguishing system for a housing in which an extinguishing-agent tank having chemical liquids as extinguishing agents is arranged, NOVEC 1230, HFC 227a, HFC 125, Fett Ex, argon or N2 being used as extinguishing agents, in the process a propellant discharging the extinguishing agent from a charging cartridge. In any case, the extinguishing-agent tank represents a pressure vessel.
DE 696 01 861 T2 describes a fire-extinguishing agent that comprises an at least partially fluorinated compound, and a method for extinguishing, fighting or preventing fires using such compositions, C4F9OCH3 also being one of the means mentioned for fighting fires.
The vapor pressure of the synthetic liquid extinguishing agents mentioned can be between 50 and 0.1 bar at 21° C. To have a minimum pressure required for discharge, synthetic liquid extinguishing agents having a vapor pressure that is too low are superimposed with a gas, for example nitrogen, permanently or with pressure when triggering. During storage, transportation, conveying, and discharging by means of extinguishing nozzles in systems of this type it is therefore assumed that these extinguishing agents are gases for which pressure vessels, extinguishing nozzles, valves, pipeline networks, filling and monitoring devices, and special components are required that need certification and are expensive, which leads to the situation that erection and operation of fire-extinguishing systems using synthetic liquid extinguishing agents are really expensive. All components of the extinguishing system (pipes, valves, tanks, nozzles) must be designed for the corresponding pressure, at least for 25 bar. This requires a corresponding technical and financial effort. Also the pressurization used requires an additional storage volume in the pressure vessel and/or additional pressure vessels having the gas for pressurization.